title: Fetal wellbeing may be compromised during strenuous exercise among pregnant elite athletes.
abstract: OBJECTIVE
  To study fetal wellbeing and uteroplacental blood flow during strenuous treadmill running in the second trimester.
  
  
  METHODS
  Six pregnant Olympic-level athletes in endurance events aged 28-37 years and training 15-22 h per week before the pregnancy were tested once at 23-29 weeks of pregnancy. The women ran three to five submaximal workloads on a treadmill with approximately 60-90% of maximal oxygen consumption. The maternal-fetal circulation was assessed with Doppler ultrasound of the uterine and umbilical arteries before, during and after exercise.
  
  
  RESULTS
  Mean uterine artery volume blood flow was reduced to 60-80% after warming up and stayed at 40-75% of the initial value during exercise. Fetal heart rate (FHR) was within the normal range (110-160 bpm) as long as the woman exercised below 90% of maximal maternal heart rate (MHR). Fetal bradycardia and high umbilical artery pulsatility index (PI) occurred when the woman exercised more than 90% of maximal MHR and the mean uterine artery volume blood flow was less than 50% of the initial value. FHR and umbilical artery PI normalised quickly after stopping the exercise.
  
  
  CONCLUSIONS
  Exercise at intensity above 90% of maximal MHR in pregnant elite athletes may compromise fetal wellbeing.
authors.affiliation: National Center for Fetal Medicine, Trondheim University Hospital (St Olav's Hospital), Trondheim, Norway. pepes@ntnu.no
authors.forename: Kjell Å
authors.initials: KÅ
authors.lastname: Salvesen
authors.forename: Erlend
authors.initials: E
authors.lastname: Hem
authors.forename: Jorunn
authors.initials: J
authors.lastname: Sundgot-Borgen
mesh_terms: D000328:Adult; D056352:Athletes; D001919:Bradycardia / Q000196:embryology / Q000503:physiopathology; D005080:Exercise Test; D005260:Female; D005333:Fetus / Q000098:blood supply / Q000502:physiology*; D006340:Heart Rate, Fetal / Q000502:physiology*; D006801:Humans; D011247:Pregnancy / Q000502:physiology*; D011262:Pregnancy Trimester, Second; D011263:Pregnancy Trimester, Third; D012420:Running / Q000502:physiology*; D016216:Ultrasonography, Prenatal; D014469:Umbilical Arteries / Q000502:physiology*; D055815:Young Adult